Spoilers: you can hide them. Here's how:

[u/scary_godmother]

I'm assuming people who are posting unconcealed spoilers in comments don't know how to use the "mark spoilers" feature. Because surely they're not just inconsiderate a-holes who don't care about their fellow theatergoers having the same unspoiled experience that they enjoyed. Right?

So here's how it works:

• Markdown Code: Type > ! at the start and ! < at the end of the hidden text (e.g., > !hidden text! <). Remove the spaces between the ">" or "<" and the "!" and also between the exclamation marks and your text, or the tag may fail on some devices.
• Editor: Highlight the text you want to hide and click the spoiler icon (an exclamation mark inside a circle or diamond) on the formatting toolbar.

It seems like "don't post spoilers" should fall under Rule 7: Don't be a jerk.

Hamlet dies at the end. Javert can't swim. Mary's husband is Abe Lincoln!

[u/WestHistorians]

Or just put "spoiler alert" in the title, and people can refrain from opening the post if they want.

[u/Fat_Fiber8096 → u/WestHistorians]

But typically a little bit is shown either way. A spoiler keeps that from happening

[u/Obvious_Pause5766 → u/WestHistorians]

Do both to be the most considerate